The present disclosure is related generally to the field of sensing devices. More particularly, the present disclosure is related to humidity and temperature sensing devices.
Sensing devices can use a number of methods to sense phenomena that can be correlated to a desired measurement. One sensing method uses interdigitated transducers (IDTs) to convert electrical energy to mechanical energy and to convert mechanical energy to electrical energy.
The IDTs can use the mechanical energy and/or electrical energy to correlate phenomena associated with either type of energy to a characteristic. An IDT can be placed on the surface of an object and transform mechanical energy from the object to electrical energy. An IDT on the surface of an object can also transform electrical energy supplied to the IDT into mechanical energy that can be transferred to the object on which the IDT is placed.
An IDT can be included in a resonator that includes an IDT and a series of reflectors that reflect mechanical energy back to the IDT. Phenomena associated with the mechanical energy, such as the velocity of the surface waves, can be sensed and measured by the IDT. In some arrangements, the mechanical energy can be transformed back into electrical energy by the IDT.
An IDT can be included in a delay line. A delay line can include a first IDT that generates mechanical energy from electrical energy and a second IDT that receives the mechanical energy generated by the first IDT. In such embodiments, phenomena associated with the mechanical energy, such as the velocity of the surface waves, can be sensed and measured by the second IDT. The mechanical energy received by the second IDT can be transformed back into electrical energy by the second IDT.
Resonators and delay lines can use the phenomena sensed by the IDTs and correlate it to a desired measurement characteristic. Resonators and delay lines can be used to correlate phenomena associated with electrical and/or mechanical energy sensed by IDTs to measurements, such as temperature, mass loading, and/or strain/stress, among other measurements.
Sensing devices using IDTs can be limited by in their ability to measure phenomena with sufficient resolution and to transmit the measurements from the sensing devices in certain environments. Additionally, the cost, amount of time, and/or difficulty associated with manufacturing IDT based sensing devices can be high, which may not be suitable for some applications.